No. It's getting there though. As of this date (12-Sep-96), some of
the drivers are still not reentrant. What does this mean? It means that
threads making various system calls will block other threads until the
call is completed. Will it crash? No. When will the fine-threading (not
treating system calls as a single operation) work? That's currently in
the works (the 2.1.xx goal is to get the kernel 100% reentrant).

Please note that this does not mean: avoid at all costs. It means that
as you work on your threaded code, you will not have all the performance
as you might with a fully reentrant kernel. Be patient; we're getting there.